1. Field of the Invention
The invention relates to a progressive slitting apparatus.
2. The Prior Art
Frequently a workpiece, web or piece of material needs to be slit along its length into multiple strips. In the case of webs, many slitters or slitting apparatus have been proposed, primarily for single-ply webs, that is, thin webs of paper. U.S. Pat. No. 1,939,925 shows a Paper Slitting Apparatus for toilet paper where a perforating head 12 makes perforations across the width of a large roll. The perforating head 12 operates in conjunction with a bed roll 10 having grooves that receive the perforating blades on each revolution of the perforating head 12. The paper web is fed into the perforating head 12 by a backfeed roll 11 and fed from the perforating head 12 by a front feed roll 13. After the large roll is perforated, it is fed to a plurality of saw tooth slitters or cutters 14. Each slitter operates independently to completely slice through the paper web and form a plurality of narrow width, toilet paper rolls. U.S. Pat. No. 5,313,863 shows a similar device where slitting blades 12 aligned with grooves 21 in bed roll 2 form a series of parallel slits in a web. A further related device is disclosed in U.S. Pat. No. 3,293,962 where slitting blades 24, 26 aligned with grooves 22, 23 in anvils 16, 18 form a series of parallel slits in corrugated board.
U.S. Pat. No. 2,369,221 relates to the continuous production of paper strips where a pair of disc rollers 3 partially cut through opposite sides of a paper web to form two cuts that are spaced from each other in the width direction of the web. As the cut strips are pulled away from each other, the paper tears between the partial cuts to form two portions 10, 11 having half thickness. U.S. Pat. No. 4,484,500 also produces strips and waste ribbons from a web. A first slitter 78 cooperates with grooves 76 in anvil 20 to form slits on one side of the waste ribbon. Further downstream, a second slitter 102 cooperates with grooves 100 in anvil 99 to form slits on the other side of the waste ribbon. Waste ribbons from the edge of the web are carried away by removal device 90 after the first slitter, while waste ribbons from the middle of the web enter removal device 120 after the second slitter. U.S. Pat. No. 3,282,525 produces triangular shaped waste ribbons 45a, 45b and 45c in rolls of paper towels. A first slitter 26a, 26b and 26c makes a straight slit on one side of the triangular waste ribbons. A second slitter 35a, 35b and 35c is reciprocated across the width of web 25, initially away from the first slit to form the second leg of the triangle, and then back toward the first slit to complete the third leg of the triangle. The two slitting devices have independent motion controllers to move one radially and the other axially.
U.S. Pat. No. 2,897,893 entitled Score-Cut Slitting Mechanism utilizes a single slitting wheel to slit a running web. The slitting wheel is disposed within a housing including a pinion. A longitudinal bar including a rack is placed parallel to the cutter roll. The pinion can move the housing longitudinally along the rack to adjust the location of the slitter across the width of the web. The slitter includes the employment of both hydraulic pressure and pneumatic pressure to urge the slitting wheel against the web and cutter roll.
U.S. Pat. No. 4,063,476 entitled Method and Apparatus for Cutting a Continuously Moving Web includes a slide that moves along guides parallel to the roll. A circular cutter and return wheel are mounted on the cradle in opposed oblique orientations. To form a diagonal slit in the web, the cradle is pivoted into its engaged position where the circular cutter is pressed against the web and roll. The oblique position of the cutting wheel causes the slide to move across the web. After the diagonal slit is completed, the cradle pivots to the opposite side, where the return roller directs the slide back to the original start position.
Accordingly ii would be desirable to provide a slitter with multiple blades that progressively slice through a multi-ply or thick workpiece, web or material to form a single slit.